The Required Combinations: Subsection

The REQUIRED COMBINATIONS: subsection is used to specify any combinations of two words
that must always appear together in a human-readable label. This subsection states
criteria for well formed labels. This section can contain zero or more
required combination specifications. Each required combination is specified on a separate line
following the REQUIRED COMBINATIONS: keyword. Each such line should consist of exactly
two label words, and is taken to mean that the first word, if
present, must be combined with the second word. Any required prefixes or
suffixes must also be specified. Any number of lines containing required combinations
can be specified. The end of the list is taken to be
a line starting with the COMBINATION CONSTRAINTS: keyword.

Note that required combinations are not bidirectional. That is, the required combination:

WORD1 WORD2

means that WORD1 cannot appear without WORD2, but does not mean that WORD2
cannot appear without WORD1.

Required combinations are automatically enforced during translation from human-readable to internal formats.
Thus, given the above example, if the label TS WORD1 were entered, the
translation would automatically add WORD2 to the label.